A multi-view video is a set of view images obtained by taking a picture of the same object using a plurality of synchronized cameras (for example, 8 cameras) that are arranged in a line or an arc shape. The multi-view video can be applied to a stereoscopic display apparatus, and enables a viewer to see a stereophonic broadcast, a 3D broadcast, 3D DMB contents, or an FTV (free-view TV) program at his/her desired viewpoint.
FIG. 1 is a diagram schematically illustrating a general multi-view video transmitting system. In the multi-view video transmitting system, as shown in FIG. 1, a plurality of cameras 4, 6, . . . , 16, 18 capture the images of the same object, and transmit digital or analog image signals to a multi-view video encoder 40 through transmission lines 20, 22, . . . , 32, 34. The multi-view video encoder compresses data, and transmits the compressed data to a multi-view video decoder 48 through a transmission line 42, the Internet 44 or a dedicated data network, and a transmission line 46. The multi-view video decoder 48 decodes the data and outputs all or some of the frames of the multi-view video to an output device, such as a monitor 40.
The pictures of the multi-view video overlap temporally and spatially. Therefore, in order to improve the efficiency of transmission, a general multi-view video encoder performs motion prediction for removing the spatial redundancy between pictures at different viewpoints as well as motion prediction in the time.
FIG. 2 is a diagram illustrating the space-time arrangement of pictures of a multi-view video according to the related art. In the arrangement structure shown in FIG. 2, a P picture is predicted in one direction from an I picture at the first viewpoint, and is then encoded. An intermediate B picture is predicted in both directions from the I picture and the P picture and is then encoded. The pictures at the other times are encoded into B pictures that are predicted in both directions.
However, in the multi-view video encoder or an encoding method shown in FIG. 2 according to the related art, a hierarchical B picture is used in the time direction, but is not used in the view direction, which results in a low encoding efficiency of a multi-view video.
Further, in the arrangement structure of the pictures of the multi-view video according to the related art, high-quality reference pictures do not exist in the vicinities of the pictures to be encoded into the B pictures at the time or viewpoint where the picture is not encoded into the I picture or the P picture. In this case, quantization errors are accumulated in the B pictures, which causes the quality of pictures to be lowered.